Boom vang with bom vang brackets for a sailing vessel

ABSTRACT

A rigid boom vang with a center part consisting of a threaded rod with a left hand portion on one side of a combined hand/rope drum with a circular turning line cage and a right hand portion on the other side, enclosed by an outer tube. Each rod is threaded into an extension arm with a corresponding inner drive nut inside and a vang clevis on the outer side. Turning the center part by the hand/rope drum will provide a symmetrical linear movement of the extension arms, because these are mounted on the boom and mast vang brackets and therefore cannot rotate with the rods. The vang brackets are a interchangeable system of hinges with toggles, being adjustable to align with the gooseneck pin axis.

BACKGROUND OF THE INVENTION

[0001] This invention relates to a rigid boom vang with adjustablefittings for a sailing vessel.

[0002] Typically, a sailboat boom extends at an approximate right angleto the vertical mast is connected to the mast by a gooseneck with atoggle and a swivel joint, allowing the boom to swing horizontally andbeing lowered or raised at the rear end. Without a rigid vang and withsails down the boom is held by a topping lift fitted to the vessel. Withraised sails the boom is held upward by the main sail. Especially whensailing downwind or on a reach, air pressure against the mainsail forcesit to bulge and causes the end of the boom to rise.

[0003] So a vang, an adjustable device or mechanism secured between theforward portion of the mainsail boom and a location near the base of themast is used to keep the boom under control. Until a few years agotypical boom vangs were line-purchase systems, distinct from that of themain-sheet, including two or more blocks or pulleys attached to theboom, and a single line having one end secured to one of the pulleysystems, with the line having a free end which is pulled out andreleased manually by the sailor.

[0004] To support the boom while the main sail is down and thereforeeliminating the topping lift, or to counterbalance the boom in verylight wind conditions to maintain an optimum shape of the sail, theseline-purchase systems were then supplemented by a mechanical vang.Whereas the line-purchase system could only apply pulling force, themechanical vang, consisting of a telescopic strut with two tubularmembers connected by a spring, applied, when retracted, lifting force tothe boom. However, this means that the spring force must be overcome inorder to trim the sail.

[0005] There are also hydraulic driven boom vangs in use, but thesesystems, due to price, weight and complexity are generally found only onbigger yachts.

[0006] Upcoming modern sailing cloth of high strength and precisecomputer aided design require more precise sail trim to be efficientthan with the traditional materials. Also, there is a tendency lately tocontrol the heel of sailing boats rather by trimming the trailing edge(leech) of the sail, than with the main sheet. This new technique,called VANG SHEETING allows by altering the height of the rear end ofthe boom to tighten or release the leech of the sail (adding twist),thus controlling airflow in the upper third of the sail where wind andheeling force are strongest. The use of the vang enables the mainsail tobe flattened independently of mainsheet tension and as the windincreases to depower the mainsail to control heel.

[0007] As pointed out, modern sailing cloth and the growing awareness toefficiently exploit the natural power of wind has led to the use ofrigid vangs rather as trimming devices than just to keep the boom undercontrol. It is obvious that fine tuning the boom works best the morepower one could apply to it. In traditional systems this could beachieved by applying more blocks or pulleys. The disadvantages then arethe need for long lines, loss of efficiency due to friction, the needfor strong springs which have to be overcome when handling the boomvang. Further, the complete system from the boom fitting to the linestopper in the cockpit is under constant strain. A good ratio for theline-purchase system would be 8:1. Assuming a manual pulling power of 50kg and a loss due to friction of 25% would result in a pulling force of300 kg, the effective vertical part of this force applied to the boom atthis point would then be only 212 kg. The operative downward force tothe sail leech with a typical length ratio from mast to boom vangfitting to the overall boom length of 4:1 would leave only somethingmore than 50 kg. This is little for precise trimming even in moderatewinds.

[0008] Another matter of importance fitting a boom vang is that thevertical pin bolt of the boom vang bracket near the mast base must beparallel to this part of the mast and needs to be aligned with thevertical gooseneck pin, to ensure a correct horizontal movement of theboom.

[0009] The distance from the mast to the spin axis of the gooseneck pinis not standardised and different mast profiles require differentfittings. Therefore, often the entire rig including mast, boom, boomvang etc. has to be purchased from one vendor, leaving no choice formore favourable solutions.

See Also Literature

[0010] “Use of vang enables the mainsail to be flattened independentlyof mainsheet tension, and it is the most effective of all controls fordynamic tuning.” “As the windspeed increases in each gust, in flat waterwe use the vang as the primary control to flatten and depower themainsail on a gust by gust basis.”

[0011] Frank Bethwaite “High Performance Sailing” Pp. 222/294

Internet Links to Vang Sheeting

[0012] http://life-marine.de/html/Links_Vangsheeting.htm

BRIEF SUMMARY OF THE INVENTION

[0013] The present invention comprises a telescopic rigid boom vang astrimming device for sailboats with a combined hand/line drum andadjustable vang brackets.

[0014] The boom vang consists of a center part and two symmetrical outerextensions with one of them fixed to the boom the other to the mastbase.The center part is a threaded rod having a left-hand and a right-handthread portion of the same length, which are either connected by aflange, sleeve, screw bolt or other connector. A left-hand thread is athread that when viewed axially (from the end) winds in an anticlockwisedirection. A combined hand- and rope-drum unit for turning the connectedrods either by hand or rope is attached where the two threaded rods areconnecting. At one end each rod is threaded to a tubular devicecontaining a round drive nut on one end and a matching mounting device,like a clevis with or without an adapting collar on the outer end. Tokeep the extension tubes aligned each rod carries a disk bearing at theouter end which fits into the extension tube so when the tubes arethreaded on the rods they remain in line. For safety and added stabilitythe rods and that part of the extension tube which is threaded will beenclosed in an outer tube, approximately the same length as the therods, with an inner sleeve bearing at the end thus supporting the insideextension tubes. The enclosing tube is fixed centrally to the drum,therefore this tube may consist of one or two parts, depending on howthey are fixed to the drum with the rods. Turning the wheel drum eitherby hand or preferably by single continuous loop of line running roundthe drum and back to the cockpit will move the extension tubessymmetrically and apply movement between the clevis and the boom & mast.

[0015] The advantages of the described boom vang compared to line pulleysystems with a spring are, that it applies more power, that the powercan be metered precisely and that the thread drive is safer and moreconvenient to use. A linear drive with threaded rod has less frictionand a much greater purchase than having long lines running aroundseveral blocks and pulleys as in common boom vang systems. Tests withthe described boom vang have shown that one could apply effectively morethan 3 times pulling power and there is no counterforce to overcome asin spring loaded models.

[0016] Although the arrangement having the rods fixed to the centralpart is the preferred one, an alternative layout would house the rodswithin the extension arms, fixed at their ends and having the drive nutsmounted in the outer arms of the central unit. Then the tubes of theextension arms would enclose the tubes of the central unit, which wouldbe less favourable.

[0017] Using a construction with one thread rod would double the forcebut would also require twice as many rotations of the wheel for the sameextension, thus degrading quick handling.

[0018] Properly installed at an angle of 45° to the mast, due to thesymmetrical movement provided by the contrary handed rods, the linesleaving the drum will always point to the gooseneck, no matter howextended the arms of the boom vang are. So, running the drum line to aturning block near the gooseneck and from there via a mast base turningblock to the cockpit would be possible without altering position orlength of the line while shifting the boom.

[0019] The power and the amount of extension can be applied veryprecisely and directly, one turn of the drum will extend the boom adefined length without slip or stretch as in common systems where alllines are under constant strain. All tensions are kept within the systembecause the chosen threads are self locking.

[0020] A continuous loop of line to drive the boom is convenient to usebecause it avoids cluttering lines. For proper operation the line drummust engage the loose line from various positions, without having tostraighten the line from the other end. This is achieved by running theline inside the drum through a system of rollers and v-formed grips.

[0021] One of the most dangerous tasks for a sailor is packing the sailseither for reefing or storing the sails to the boom, because this cannotbe done with one hand (and the other for the boat). So usually thesailor leans the upper body upon or against the boom which is thenusually horizontally fixed by the mainsheet and grabs the sail clothwith both arms to bind it to the boom. This only can be done safely whenthe boom, under the body's weight, doesn't move downward, which is oftenthe case with spring loaded systems. So the inherent self lockingability of the thread driven systems adds important safety, specially inrough sea when the boat is in a rolling movement.

[0022] The present invention comprises additionally adjustable vangattachment brackets to a sailboat mast and boom.

[0023] Numerous forms and sizes of masts and booms would need manydifferent shaped brackets to mount a boom vang. This and the necessityto align the axis of the boom vang mast bracket bolt to that of thevertical boom gooseneck pin to maintain an even horizontal movement ofthe boom around the mast has led to the invention of an adjustable vangbracket which can be attached to flat or cylindrical shaped surfaces andhaving an adjustable vertical toggle pin axis.

[0024] This is achieved with a hinged joint system consisting of twoidentical base brackets, to which a toggle or two more hinged arms witha toggle could be mounted. In contrary to a vang mast's toggle a boombracket's toggle can be left in a fixed position to the boom. So theboom vang bracket incorporates only two identical base hinges with theholes for rivets, screws or a T-notch boom plate. One base hinge turned180° fits into the other and the toggle can be inserted between them onthe common bolt. The connecting pin of the vang clevis mounted on thetoggle allows the boom to vertically swing around the gooseneck'shorizontal pin.

[0025] A boom vang mast bracket then consists of two base hinges asdescribed before, complemented with two other hinged arms, again ofidentical shape but one of them turned 180°, to fit into the other andcarrying a toggle on their connecting bolt. This arrangement thenpermits a boom vang mast bracket's toggle to turn around its axis morethan 180°, whenever this is needed to follow the boom's movement. Thebracket's base aligns itself to the angle of the holding ground becauseit can turn around its axis. The hinged bracket base plates have aconcave surface on the underside that will ensure a continuous contactalong their sides to any flat or cylindrical surface as long as thatradius is bigger than the concave radius of the base brackets.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0026]FIG. 1 is a diagram showing, in part section, a vang, inaccordance with the invention, and its connections to main-boom andmain-mast of a yacht. An extended vang is shown with broken lines. FIG.1 is supposed to be the frontpage view;

[0027]FIG. 2 is a diagram showing a view of a left hand and a right handthread rod connected by a central flange and having disc bearings at theouter ends;

[0028]FIG. 3 is combined hand/rope drum with cylindrical fitting,consisting of a symmetrical pair, with a grip and a roller cage betweenthe halves;

[0029]FIG. 4 is a section view of a set of two enclosing tubes withsleeve bearings on each outside end;

[0030]FIG. 5 is a sectional view of the center part as an assembly ofFIG. 2, FIG. 3 and FIG. 4;

[0031]FIG. 6 is a sectional view of an extension tube with a left handdriving nut on the inside end;

[0032]FIG. 7 is a sectional view of an extension tube with a right handdriving nut on the inside end;

[0033]FIG. 8 is a cross-section view of an assembled thread driven boomvang;

[0034]FIG. 9 is an enlarged sectional view of the left end of theenclosing tube with a sleeve bearing of the central unit and the leftend of a thread rod with a disc bearing attached.

[0035]FIG. 10 is an enlarged sectional view of the center part of thehand-rope-drum, showing the rods, connected through the center flange,the drum connected to the flange by screws and the enclosing tubesconnected to the drum.

[0036]FIG. 11 is an enlarged sectional view of a thread rod runningthrough a drive nut which is kept centered by its flange to the innerwall of the enclosing tube.

[0037]FIG. 12 is a frontal view of the combined hand/rope drum with onehalf of the drum removed to show a rope running between radial grips anda roller cage with arrows to indicate their movements;

[0038]FIG. 13 is a plane sectional view of two identical base bracketsone turned 180° with fixing holes and hinge bearings for a vang fitting;

[0039]FIG. 14 shows a sectional view of toggle with a vertical bolt holeand a horizontal pin hole;

[0040]FIG. 15 is a view of two assembled base brackets as in FIG. 13connected by a bolt, with a toggle attached;

[0041]FIG. 16 is a frontal view of FIG. 15 attached to a boom profile;

[0042]FIG. 17 is a sectional view of two identical hinges one turned180°;

[0043]FIG. 18 is a view of a vang mast fitting with two base brackets,two hinges and a toggle;

[0044]FIG. 19 is a topside view of a vang mast fitting with two basehinges close together;

[0045]FIG. 20 is a topside view of a vang mast fitting with two basehinges at maximum distance to each other on a mast profile;

[0046]FIG. 21 is a view of prefabricated profils for base hinges andhinge arms, rotary grinded and cut to different brackets;

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0047] A rigid vang 1 according to this description fitted to a boom 2and a mast 3 is shown in FIG. 1. If properly installed in a 45° positionto the horizontal boom and the vang mast bracket pin 4 aligned to thevertical gooseneck 5 pin, the operating line 6 leaving the drum 7 with a90° angle to its turn axis, always points to the gooseneck 8, regardlessof the boom vang extension, as it is shown by a dotted line with anextended vang 9. From two sheave blocks 10, one on each side of thegooseneck the lines run down to a turning block 11 at the foot of themast and from there to the cockpit. This is a preferable line operatinglayout, because it avoids cluttering, as might occur if the lines wereleading directly from the boom vang drum to the cockpit.

[0048] The most distinctive part of the boom vang is shown in FIG. 2. Aleft-hand 12 and a right hand 13 threaded rod are face side connected toa flange 14. The connection could be arranged by various methods, hereit is assumed that a cylindrical lathed part 15 of one rod end fitsthrough a center hole of the flange 14 into a matching cylindrical holeof the other rod end and that all parts are welded, soldered or brazedtogether FIG. 10. That way the inner sides of a combined hand/rope drumconsisting of two halves, are mounted to both sides of the flange 14,enclosing it and held together by a releasable connection as by bolts17, either to the flange or through punches in the flange to thecorresponding half drum part.

[0049] Two enclosing tubes 18/19 which are pressed, bonded or by anyother appropriate way fixed to the cylindrical parts 20 of the drumhalves will complete the center part 21 of the boom vang leaving theline mechanism 22 inside the drum for later explanation.

[0050] The center part of the boom vang FIG. 5 will house the extensiontubes 23/24 which will enclose the threaded rods 12/13 by correspondingdrive nuts 25/26 and are, depending on the position of the drive nuts onthe rods, partly enclosed by the outer tubes 18/19. To keep the rodscentered, disks 27 are added at each rod end, acting as bearings to theinner walls of the extension tubes 23/24, whereas the enclosing outertube ends of the center part will house bushings 28 to guide them. Theextension tubes are threaded to the rods, one by a left hand nut 25 andthe other by a right hand nut 26. These nuts could be machined directlyinto the tubes 23/24, but a favourable solution as shown in FIG. 10 isto bolt or bond them as separate items into the tube ends.

[0051] To add more stability and to keep the extension tubes fixed tothe drive nuts under heavy pressure the drive nuts have collar flanges29 which will also guide the extension tubes through the enclosing outertubes. Thus the extension tubes are well supported to the rods and theenclosing tubes by the thread of the drive nuts 25/26, the disks 27 atthe end of the rods, by the flange shoulders 29 of the drive nuts 25/26and the bushings 28 at the outer enclosing tubes.

[0052] Turning the drum, with the clevis ends 30 of the extension armsfixed to the vang mast 31 and vang boom fittings 32 will symmetricalmove the extension arms out or in, heaving or lowering the boom aroundthe gooseneck's horizontal pin 16. In this description the threaded rodsare preferably mounted centrally to a flange, but the same principlecould be applied by having two rods fixed inside the extension arms andhaving the drive nuts fitted to the outer ends of the central part 21.Then the outer arms 23/24 would enclose the tubes 18/19 of the centralpart.

[0053] Because these threads are self locking on the drive nuts 25/26,the unit could be used as described until now without lines by turningthe drum manually. However, most commonly the boom vang will be operatedfrom the cockpit. Therefore the drum will have an internal system ofrollers 33 and V-shaped grips 34 to engage the incoming line 35 to thedrum 7 even when the pulled outgoing line doesn't have any counter forceon the feeding side in order to straighten the line and get grip to thedrum. So the feeding end of the rope may hang loose.

[0054]FIG. 12 shows a frontal view of the inside of a drum-half with arope 35, rollers 33 with their pins 36, v-shaped grips 34 and a movablecage 37 with pin holes to keep rollers and pins fixed at their relativeposition. The rectangular plates 34 with a V-shaped inner contour withsharp edges called grips 32, are fitted into corresponding centric slots38 inside each drum half, thus connecting and positioning the two drumparts to each other. An outer centric groove 39 of each drum halfcarries a semi-circular plate, called here cage-plate 37, with holes forroller pins 40 and another groove 41 that keeps the roller pins in acircular position. Between the two cage-plates rollers 33 are mounted,held by pins 40 whose ends are free to circulate in their groove. Whenthe drum halves are bolted to their corresponding tapping holes 42 or tothe flange 14, the cage unit 22 with the rollers can freely circulartearound the thread rod axis 43 inside the drum.

[0055] The vang sheet's operating line 6 is fed between the V-shapedgrip plates 34 and the rollers 33; in case of an infinite loop the drumhalves have to be dismantled to position the line between the gripplates and the rollers. Pulling the line on one end will straighten theline inside the drum, pressing it into the v-shaped cutout and jammingit there, thus applying torque and turning the drum. The rollers of thecage will press the line into the V-shaped cutouts and prevent it fromfalling out if the line is hanging headover, having no tension at theincoming side. The rollers 33 at the end 44 of the semicircular cagewill ease the feed of the line into and out of the drum. The cage withthe rollers will circle only a limited way until the tension force ofthe pulling line will prevent this movement, but the drum itself willmove against the cage when the drum is turned. To adjust the rope drumto different kind and sizes of ropes, the V-grips 32 are plugged intotheir radial slots 45 and can be changed like the rollers to fitdifferent shapes and sizes and rope materials.

[0056] This principle of rope-drum operation with a moving line cagemight also be used for other gear like backstay adjusters or sailfurlers on sailboats.

[0057] The invention describes further a bracket system developedpredominantly for boom vang fittings at the mast and boom 31/32, butwhich can be used also for every kind of mounting brackets, as for radardomes or antennas on flat or cylindrical shaped surfaces.

[0058] To provide a clean function of a boom vang, the axis of itshorizontal turning point, which is the vertical pin of its vang mastbracket 4 must be aligned with that of the boom, which is the verticalpin S of the gooseneck bracket 8. If not, the two different radius, one,which is the horizontal part of the length of a mounted boom vang 1, andthe other that of the boom's turning axis at the gooseneck pin 5 to thevangs boom connecting bolt 46, would result in an up or down movement ofthe boom's outboard end while being turned.

[0059] This problem will be solved by a bracket consisting of a hingesystem where one of the hinge bolts carries a toggle 47 on which theclevis end 30 of a rigid boom vang can be mounted. The basic form of aboom vang bracket consists of two identical base hinge plates 48 with aconcave underside and holes 49 for bolts or rivets. The underside 50 ofthese base hinges will be in continuous contact with their lengthwiseedges 51 on surfaces as long as their concave-radius remains smallerthan that of the holding ground 52. Rotated by 180° one of the identicalhinges fits the other connected by a common bolt 53, leaving space for atoggle 47 on the same bolt.

[0060] Having the freedom to rotate around the common bolt 53 the basicplates 48 can adjust to different cylindrical surfaces 52 as found ondifferent booms. Adding another hinge arm 54 to each base bracket willgive a double hinge which then can carry more hinges or a toggle on thecommon axis 55 of both added arms. Again these additional hinge arms areof identical shape, one of them turned around 180° will fit into theother leaving space on the common axis to fit a toggle. Changing thedistance of the the base plates 48 being apart 56 alters the anglebetween the added hinge arms 54 and thus determines the distance 57 oftheir common bolt together with that of the toggle axis to the mastsurface 58. This way it is possible to align the boom vang mast bracketpin to that of the gooseneck's vertical pin. Using identical basic partsfor the mast and the boom fitting and using same parts turned 180° forboth sides of the hinge is very economical to produce these brackets.Long strips of prefabricated profiles 59 with holes can be used fordifferent length of hinges. As the holding power of the brackets isdependent on the number of connecting rivets or bolts to the surface,different lengths of hinges with resulting numbers of holes will providedifferent brackets of different strength. FIG. 21 shows that bydetermining the length and the cutting width 60 of rotary grinding fromthe prefabricated strips, produces a family of different brackets.Another advantage is that changing a smaller bracket for a stronger onewill require only the additional new holes in sensitive rig equipment.

1. I claim the invention of a linear thread driven rigid boom vang whichwill extend or contract two outer arms with clevis ends by a left handand a right hand thread rod, either by turning a center part with thefixed left and right handed rods into and out corresponding drive nutsfixed in the outer arms or by turning the central part with fixed lefthand drive nut on one end and a right hand drive nut on the other endaround corresponding handed rods fixed inside two outer arms.
 2. Ifurther claim the invention of a thread driven boom vang as specified inclaim 1 with a combined hand/rope drum consisting of two halves whichenclose radial mounted, to the outside V-shaped plates connected to thedrum and a semicircular cage with rollers which can move circular aroundthese plates and the drum axis and which keeps a line fed inside the twohalves of the drum between the rollers and V-shaped plates in which theline is jammed when the outgoing line is pulled, thus turning theengaged drum around the roller cage which keeps the line fed, griped andprevents it from falling out.
 3. I also claim the invention of a systemof brackets consisting of two base brackets with attached hinges and atoggle being able to adjust the turning axis of a boom vang mast bracketby setting the base brackets further apart on the fixing underground andto fit flush various shapes and seizes of masts and booms or flat andcylindrical surfaces, by two identical base brackets with concaveunderside which, one turned 180° to fit the other adjust themselvesflush to the fixing underground and which each at least carry one morehinge with one of them turned 180° will also fit the other and which arethen connected by a bolt carrying a toggle or arm for mountingequipment.